Luminescent Pt(II) Complexes Using Unsymmetrical Bis(2-pyridylimino)isoindolate Analogues

A series of ligands based upon a 1,3-diimino-isoindoline framework have been synthesized and investigated as pincer-type (N∧N∧N) chelates for Pt(II). The synthetic route allows different combinations of heterocyclic moieties (including pyridyl, thiazole, and isoquinoline) to yield new unsymmetrical ligands. Pt(L1–6)Cl complexes were obtained and characterized using a range of spectroscopic and analytical techniques: 1H and 13C NMR, IR, UV–vis and luminescence spectroscopies, elemental analyses, high-resolution mass spectrometry, electrochemistry, and one example via X-ray crystallography which showed a distorted square planar environment at Pt(II). Cyclic voltammetry on the complexes showed one irreversible oxidation between +0.75 and +1 V (attributed to Pt2+/3+ couple) and a number of ligand-based reductions; in four complexes, two fully reversible reductions were noted between −1.4 and −1.9 V. Photophysical studies showed that Pt(L1–6)Cl absorbs efficiently in the visible region through a combination of ligand-based bands and metal-to-ligand charge-transfer features at 400–550 nm, with assignments supported by DFT calculations. Excitation at 500 nm led to luminescence (studied in both solutions and solid state) in all cases with different combinations of the heterocyclic donors providing tuning of the emission wavelength around 550–678 nm.


Contents
Figure S1 1 H NMR spectrum of 1 in CDCl3 (500 MHz).Inset shows loss of NH peaks via D2O exchange.

Figure S4
Infrared spectrum of 1.

Figure S12
Infrared spectrum of HL 2 .

Figure S16
Infrared spectrum of HL 3 .

Figure S43
Infrared spectrum of Pt(L 6 )Cl.Table S1 Data collection parameters for the X-ray crystal structure Figure S44 Packing diagram for the X-ray crystal structure

Figure
Figure S1. 1 H NMR spectrum of 1 in CDCl3 (500 MHz).Inset shows loss of NH peaks via D2O exchange.

Figure S44 .
Figure S44.Packing diagram obtained from the X-ray structure of Pt(L 5 )Cl.